Fixing apparatus and image forming apparatus

Abstract

Provided is a fixing apparatus employing an external heating method in which a scratch on a belt member and slippage of the belt member are prevented. The fixing apparatus includes: a fixing roller; a pressure member pressed against the fixing roller; an endless belt which is rotatably supported and contacts the fixing roller surface for heating the fixing roller; and heating means for heating the endless belt. By passing a recording material through a nip between the fixing roller and the pressure member, the fixing apparatus fixes an unfixed toner image on the recording material on which the unfixed toner image is transferred. The fixing apparatus further includes a cleaning member for removing dirt adhered to a surface of the endless belt by contacting the surface of the endless belt in a region where the endless belt is not supported.

1. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, wherein: 
 the cleaning member is a scraper including a plate member having an edge being in contact with the surface of the endless belt so that the dirt adhered to the surface of the endless belt is removed, and 
 the scraper includes: 
 a bending portion at which the plate member is bent; 
 a cleaning section which is a part of the plate member from the edge to the bending portion; 
 a supporting section which is a part of the plate member from the bending portion to another edge of the plate member, the supporting section being fixed to a housing of the fixing apparatus, and 
 the scraper having, at the bending portion, an opening which cuts in the plate member in a direction intersecting a straight line made by the bending portion. 
 
     
     
       2. The image forming apparatus as set forth in  claim 1 , wherein:
 the endless belt is suspended and supported by the fixing roller and at least one suspending roller; 
 the pressure member applies pressure against the fixing roller via the endless belt; 
 the unfixed toner image is fixed on the recording material in such a manner that the recording material on which the unfixed toner image is transferred is passed through a nip between the pressure member and an outer surface of the endless belt which outer surface is on a side not being in contact with the fixing roller; and 
 the cleaning member is in contact with the outer surface of the endless belt. 
 
     
     
       3. The image forming apparatus as set forth in  claim 1 , wherein:
 the scraper is made of metal. 
 
     
     
       4. The image forming apparatus as set forth in  claim 1 , wherein:
 a surface of the scraper is coated with a coating made of fluororesin. 
 
     
     
       5. The image forming apparatus as set forth in  claim 4 , wherein:
 the coating is made of a material different from a surface layer material for the surface of the endless belt which surface is in contact with the scraper. 
 
     
     
       6. The image forming apparatus as set forth in  claim 1 , further comprising:
 a containing member, provided below the cleaning member, for storing the dirt that the cleaning member has removed from the endless belt. 
 
     
     
       7. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, 
 wherein: 
 the endless belt is suspended and supported by a plurality of suspending rollers; 
 an outer surface of the endless belt is in contact with the fixing roller, the outer surface being on a side not being in contact with the plurality of suspending rollers; and 
 the cleaning member is in contact with the outer surface of the endless belt. 
 
     
     
       8. The image forming apparatus as set forth in  claim 7 , wherein:
 the outer surface of the endless belt is made of a same material as that for the surface of the fixing roller. 
 
     
     
       9. The image forming apparatus as set forth in  claim 7 , wherein:
 the outer surface of the endless belt is made of a material having a lower toner releasability than that of the surface of the fixing roller. 
 
     
     
       10. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, 
 wherein: 
 the cleaning member is a scraper including a plate member having an edge being in contact with the surface of the endless belt so that the dirt adhered to the surface of the endless belt is removed, and 
 the scraper includes: 
 a plurality of bending portions at which the plate member is bent, the plurality of bending portions being parallel to each other; 
 a cleaning section which is a part of the plate member from the edge to the plurality of bending portions; and 
 a supporting section which is a part of the plate member from the plurality of bending portions to another edge of the plate member, the supporting section being fixed to a housing of the fixing apparatus. 
 
     
     
       11. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, 
 wherein: 
 the cleaning member is a scraper including a plate member having an edge being in contact with the surface of the endless belt so that the dirt adhered to the surface of the endless belt is removed, 
 a plurality of said scrapers are arranged in such a manner that the plurality of said scrapers are in contact with the endless belt in order along a rotational direction of the endless belt, and 
 the scrapers being in contact with the endless belt at more downstream contacting points in the rotational direction of the endless belt are pressed against the endless belt with greater pushed amounts, each of the pushed amounts being a distance for which the endless belt is pushed down at the respective contacting point at which the respective scraper is pressed against the endless belt. 
 
     
     
       12. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, 
 wherein: 
 the cleaning member is a scraper including a plate member having an edge being in contact with the surface of the endless belt so that the dirt adhered to the surface of the endless belt is removed, and 
 a contacting angle is greater than 90°, the contacting angle being an angle made by (i) a part of the surface of the endless belt which part extends, toward an upstream of the rotational direction of the endless belt, from a contacting point at which the endless belt and the scraper are in contact with each other and (ii) a surface of the scraper which surface faces the upstream of the rotational direction of the endless belt and includes said contacting point. 
 
     
     
       13. The image forming apparatus as set forth in  claim 12 , wherein:
 the contacting angle is within a range of 135° or greater but not greater than 165°. 
 
     
     
       14. An image forming apparatus comprising a fixing apparatus that fixes an unfixed toner image on a recording material on which the unfixed toner image has been transferred, said fixing apparatus comprising:
 a fixing roller; 
 a pressure member for applying pressure against the fixing roller, wherein the recording material is passed through a nip between the fixing roller and the pressure member to fix the unfixed toner image on the recording material; 
 an endless belt which is rotatably supported and heats the fixing roller by being in contact with a surface of the fixing roller; and 
 heating means for heating the endless belt, 
 said fixing apparatus further comprising; 
 a cleaning member for removing dirt adhered to a surface of the endless belt by being in contact with the surface of the endless belt in a region where the endless belt is not supported, 
 wherein: 
 the cleaning member is a scraper including a plate member having an edge being in contact with the surface of the endless belt so that the dirt adhered to the surface of the endless belt is removed, and 
 a pushed amount for which the scraper pushes down the endless belt is 0.3 mm or more but not more than 1 mm, the pushed amount being a distance for which the endless belt is pushed down at a contacting point at which the scraper is pressed against the endless belt.